Microfiltration and ultrafiltration equipment is required for many applications including the concentration, fractionation and buffer exchange of protein solutions, the depyrogenation of water and intravenous solutions, the desalting of biological and the removal of macromolecules and colloids. A well-known type of such equipment employs a filtration cassette comprising a stacked array of filtration membranes separated by flow accommodating screens and retained between demountable plates. At least one of these demountable plates is a distributor plate and contains a channel system for supply of feed to and collection of retentate and permeate from the cassette. The channel system is in fluidic communication with the cassette via apertures on the plate surface, aligned in registry with corresponding apertures on the cassette. When such equipment is used in the manufacture of biopharmaceuticals it is critical that it is easy to sanitise, with no deadlegs and with pore-free polished flow-path surfaces. Further, it is essential that the entire flow-path system can be drained between runs without leaving pools of remaining liquid in the equipment. Full drainage improves product recovery and also allows for total area utilisation in an air integrity test.
GB2348381A describes a distributor plate for filter cassettes with a channel system that branches out from two end surfaces of the plate. This plate has horizontal channels which can give rise to incomplete draining. Hence, there remains a need for distributor plates with improved draining properties.